4 9-1 What Are Major Threats to Forest Ecosystems?Concept 9-1 Ecologically valuable forest ecosystems are being cut and burned at unsustainable rates in many parts of the world.

5 Types of ForestsForests cover 30% of earth’s land surfaceOld-growth forests: uncut or regenerated primary forest that has not been seriously disturbed by human activities or natural disasters for several hundred years or moreSecond-growth forests: a stand of trees resulting from secondary ecological succession. Develop after trees have been removed by human activities such as clear cutting for timber or cropland or by natural forces such as fire, hurricanes, or volcanic eruptionTree plantation; tree farm; commercial forest

6 Old growth forest in the US state of Washington’s Olympic National ForestFig. 9-2, p. 180

7 rapidly year round so rotation cycle can be 6-10 years.Short (25- to 30- year rotation cycle of cutting and regrowth of a monoculture treeplantation in modern industrial forestry. In tropical countries, trees grow morerapidly year round so rotation cycle can be 6-10 years.Fig. 9-3, p. 180

8 Old growth or second growth forest are clear cut to provide land for growing mosttree plantationsFig. 9-3, p. 180

9 ital Forests Ecological Economic Services ServicespFigure 9.4: Major ecological and economic services provided by forests (Concept 9-1).Question: Which two ecological services and which two economic services do youthink are the most important?italForestsEcologicalServicesEconomicServicesSupport energy flow and chemical cyclingFuelwoodLumberReduce soil erosionPulp to makepaperAbsorb and release waterPurify water and airMiningFigure 9.4: Major ecological and economic services provided by forests (Concept 9-1).Question: Which two ecological services and which two economic services do youthink are the most important?LivestockgrazingInfluence local and regional climateStore atmospheric carbonRecreationProvide numerous wildlife habitatsJobsFig. 9-4, p. 181

10 Science Focus: Putting a Price Tag on Nature’s Ecological ServicesEstimated value of earth’s ecological services$33.2 trillion per year$4.7 trillion per year for forestsThis is hundreds of times the economic valueNeed to start factoring values into land useEcological services can be a sustainable source of ecological income

12 Harvest Methods Step one: build roads Erosion Invasive speciesOpen up for human invasionStep two: logging operationsSelective cutting: intermediate aged or mature trees in an uneven aged forest are cut singly or in small groups (Fig 9-6a)Clear cutting: remove all the trees from an areaStrip cutting: involves clear cutting a strip of trees along the contour of the land within a corridor narrow enough the allow natural regeneration within a few years

13 Cleared plots for grazing New highway Highway Cleared plotsfor agricultureOld growthFigure 9.5: Natural capital degradation: Building roads into previously inaccessible forests is the first step to providing timber, but it alsopaves the way to fragmentation, destruction, and degradation of forest ecosystems.Fig. 9-5, p. 182

14 (a) Selective cutting Clear streamMajor tree harvesting methods. If you were cutting trees in a forest you ownedwhich method would you choose and why?(a) Selective cuttingFigure 9.6: Major tree harvesting methods.Question: If you were cutting trees in a forest you owned, which method would you choose and why?ClearstreamFig. 9-6, p. 182

15 (b) Clear-cutting Muddy streamFigure 9.6: Major tree harvesting methods.Question: If you were cutting trees in a forest you owned, which method would you choose and why?MuddystreamFig. 9-6, p. 182

16 (c) Strip cutting Cut 1 Uncut year ago Dirt road Cut 3–10 years agoFigure 9.6: Major tree harvesting methods.Question: If you were cutting trees in a forest you owned, which method would you choose and why?ClearstreamFig. 9-6, p. 182

18 Forests and Fires Surface fires Burn only undergrowth and leaf litterMay kill seedlings and small trees but spare most mature trees; allow most wild animals to escapeCool fireEcological benefits: help prevent more destructive fires, free mineral nutrients, release certain seeds and stimulate germination of some tree seeds, help control diseases and insects

22 Loss of Original ForestsDeforestationOver past 8,000 years, human activities have reduced the earth’s forest by 46%, most of this loss since since 1950Most in tropical areas, developing countriesEstimated loss of 40% intact forests within next 20 yearsDeforestation= temporary or permanent removal of large expanses of forest for agriculure, settlements, or other uses

23 Extreme tropical deforestation in Chiang Mai,Thailand. What do you think will happen to the dried out topsoil when the winds come?How does the term ecological tipping point apply here?Such clearing of trees, which absorb carbon dioxide as they grow, contributes to projected climate change. It also dehydrates the soil by exposing it to sunlight. The dry topsoil can then blow away, which can lead to irreversible ecological tipping point beyond which a forest cannot be reestablished in the area.Fig. 9-9, p. 184

25 Good News on Forests2000–2007 net total forested area stabilized or increasedMost of the increase due to tree plantationsNet loss of terrestrial biodiversity

26 Return of Forests in the United States (1)U.S. forestsCover ~30% of landContain ~80% of wildlife speciesSupply ~67% of nation’s surface waterForest cover greater now than in 1920Secondary succession

27 Return of Forests in the United States (2)Second- and third-growth forests fairly diverseMore wood grown than cut40% of forests in National Forest SystemSome forests transformed into tree plantations

28 Tropical Forests Cover 6% of earth’s land areaHabitat for 50% of terrestrial plants and animalsVulnerable to extinction – specialized nichesRapid loss of 50,000–170,000 km2 per yearSome second-growth forestsTropical forests once covered at least twice as much land area as they do todayBrazil, for example, has more than 30% of world’s remaining tropical rain forest in its vast Amazon basinSecond growth forests do not have same biodiversity as old-growth forests

29 Causes of Tropical Forest Deforestation and DegradationPopulation growth and povertyEconomic reasonsLoggingRanchingFarmingGovernment subsidiesFires raise temperatures and reduce rainfallGovernment subsidies can accelerate deforestation by reducing the costs of timber harvesting, cattle grazing, and establishing vast plantations of crops such as soybeans and oil palms

30 Natural Capital DegradationMajor Causes of the Destruction and Degradation of Tropical ForestsBasic CausesSecondary CausesNot valuing ecological servicesCrop and timber exportsGovernment policiesPovertyPopulation growthRoadsFiresSettler farmingCash cropsCattle ranchingLoggingTree plantationsCattle ranchingTree plantationsLoggingCash cropsSettler farmingFigure 9.11: Major interconnected causes of the destruction and degradation of tropical forests. The importanceof specific secondary causes varies in different parts of the world. Question: If we could eliminate the basic causes,which if any of the secondary causes might automatically be eliminated?FiresRoadsFig. 9-11, p. 186

31 What’s going on in this picture?Brazil’s Amazon basinWhat’s going on in this picture?Large areas of tropical forest in Brazil’s Amazon basin are burned each year to make way for cattle ranches, plantation crops, and small scale farms.Fig. 9-12, p. 187

32 9-2 How Should We Manage and Sustain Forests?Concept 9-2 We can sustain forests by emphasizing the economic value of their ecological services, removing government subsidies that hasten their destruction, protecting old-growth forests, harvesting trees no faster than they are replenished, and planting trees.

37 Trees and Paper Many trees are cut for paper production AlternativesPulp from rice straw and agricultural residues (China)Kenaf (U.S.)Hemp

38 KenafSolutions: Pressure to cut trees to make paper could be greatly reduced by planting and harvesting a fest-growing plant known as kenaf. USDA calls kenaf “the best option for paper making in the US”Fig. 9-14, p. 189

41 9-3 How Should We Manage and Sustain Grasslands?Concept 9-3 We can sustain the productivity of rangeland by controlling the number and distribution of grazing livestock and by restoring degraded grasslands.

42 Grasslands Provide important ecological servicesSecond most used and altered ecosystem by humans42% grazed by cattle, sheep, and goats – rangeland (open) and pasture (fenced)Overgrazing

45 In the mid-80s cattle had degraded the vegetation and soil on this stream bank alongside the San Pedro River in ArizonaFig. 9-17, p. 191

46 Within 10 years, the area was restored through natural regeneration after grazing and off-road vehicle use were bannedFig. 9-17, p. 191

47 9-4 How Should We Manage and Sustain Parks and Nature Reserves?Concept 9-4 We need to put more resources into sustaining existing parks and nature reserves and into protecting much more of the earth’s remaining undisturbed land area.

48 National Parks >1,100 national parks in 120 countriesOnly 1% of parks in developing countries are protectedLocal people invade parks to surviveLoggingMiningPoaching

49 Problems Protecting National ParksIllegal loggingIllegal miningWildlife poachingMost parks too small to protect large animalsInvasion of nonnative species

50 Stresses on U.S. National Parks58 major national parksBiggest problem is popularityDamage from nonnative speciesThreatened islands of biodiversityNeed $6 billion for overdue repairs

51 Nature Reserves Occupy a Fraction of Earth12% of earth’s land protectedOnly 5% fully protected – 95% reserved for human useNeed for conservationMinimum 20% of land in biodiversity reservesProtection for all biomes

53 Science Focus: Reintroducing the Gray Wolf to Yellowstone National ParkReduced to a few hundred in lower 48 by 1973Keystone speciesRestoration proposal angered ranchers, hunters, loggersreintroduced in Yellowstone, 124 by 2008Positive ripple effect after reintroduction

54 The Gray Wolf and Yellowstone National Park: After becoming almost extinct in much of the US, the gray wolf was listedAnd protested as an endangered species in Despite intense opposition from ranchers, hunters, miners, and loggers, 31 members of this keystone species were reintroduced to Yellowstone National Park in 1995 and In 2008, there were about 124 gray wolves in the park.Fig. 9-B, p. 193

58 Case Study: Controversy over Wilderness Protection in the U.S.1964 Wilderness ActTen-fold increase from 1970 to 20084.6% of U.S. land protected, 75% of that in Alaska

59 9-5 How Can We Help to Sustain Terrestrial Biodiversity?Concept 9-5 We can help to sustain terrestrial biodiversity by identifying and protecting severely threatened areas (biodiversity hotspots), rehabilitating damaged ecosystems (using restoration ecology), and sharing with other species much of the land we dominate (using reconciliation ecology).

60 Three Principles to Protect EcosystemsMap and inventory the world’s terrestrial and aquatic ecosystemsLocate and protect the most endangered ecosystems, with a focus on biodiversitySeek to restore as many degraded ecosystems as possible

62 34 biodiversity hotspots identified by ecologists as important and endangered centersof terrestrial biodiversity that contain a large number of species found nowhere else.Identifying and saving these critical habitats requires a vital emergency response.34 biodiversity hotspots identified by ecologists as important and endangered centersof terrestrial biodiversity that contain a large number of species found nowhere else.Identifying and saving these critical habitats requires a vital emergency response.Fig. 9-19, p. 196

64 Ecological RestorationRestoration: returning a particular degraded habitat or ecosystem to a condition as similar as possible to its natural stateRehabilitation: turning a degraded ecosystem into a functional or useful ecosystem without trying to restore it to its original condition ex. Removing pollutants and replanting to reduce soil erosion in abandoned mining sitesReplacement: replacing a degraded ecosystem with another type of ecosystem ex. A degraded forest could be replaced by a pasture or tree plantationCreating artificial ecosystems: ex. Creating artificial wetlands to help reduce flooding or treat sewage

65 Science-based Principles for RestorationIdentify cause of degradationStop abuse by reducing factorsReintroduce species if necessaryProtect area from further degradation

66 Case Study: Ecological Restoration of Tropical Dry Forest in Costa RicaOne of world’s largest ecological restoration projectsRestore a degraded tropical dry forest and reconnect it to adjacent forestsInvolve 40,000 people in the surrounding area – biocultural restorationEcotourism

67 Restoration EcologyCreating new habitats to conserve species diversity in areas where people live, work, playPeople learn to protect local species and ecosystemsSustainable ecotourismGolden Gate Park in San Francisco

69 9-6 How Can We Help to Sustain Aquatic Biodiversity?Concept 9-6 We can help to sustain aquatic biodiversity by establishing protected sanctuaries, managing coastal development, reducing water pollution, and preventing overfishing.

71 Impacts on Aquatic Ecosystems (2)Freshwater habitat disruptionDamsWater withdrawals from riversLikely extinction34% marine fish species71% freshwater speciesGreater than any other group of species

72 Area of ocean bottom before a trawler net scraped it like a gigantic plow.Fig. 9-21, p. 199

73 The same area after the trawler scraped the ocean bottomThe same area after the trawler scraped the ocean bottom. According to marine biologistEllie Norse, “Bottom trawling is probably the largest human-caused disturbance to thebiosphere.” Trawler fishers disagree and claim that the ocean bottom life recovers aftertrawling.TThe same area after the trawler scraped the ocean bottom. According to marine biologistEllie Norse, “Bottom trawling is probably the largest human-caused disturbance to thebiosphere.” Trawler fishers disagree and claim that the ocean bottom life recovers aftertrawling.Fig. 9-21, p. 199

75 Collapse of Canada’s 500 year old Atlantic cod fishery off coast of NewfoundlandGraph illustrating the collapse of Canada’s 500 year old Atlantic cod fishery off the coast of Newfoundland. Beginning in the late1950s, fishers used bottom trawlers to capture more of the stock, reflected in the sharp rise in this graph. This resulted in extremeoverexploitation of the fishery, which began a steady fall throughout the 1970s, followed by a slight recovery in the 1980s, and totalcollapse by 1992, when the site was closed to fishing. Despite a total ban on fishing, the cod population has not recovered. This hasput at least 20, 000 fishers and fish processors out of work and severely damaged Newfoundland’s economy.Fig. 9-22, p. 200

78 Why Is Protection of Marine Biodiversity So Difficult?Human aquatic ecological footprint expandingNot visible to most peopleViewed as an inexhaustible resourceMost ocean areas outside jurisdiction of a country

81 Three Big Ideas from This Chapter - #1The economic values of the important ecological services provided by the world’s ecosystems need to be included in the prices of goods and services.

82 Three Big Ideas from This Chapter - #2We can sustain terrestrial biodiversity by protecting severely threatened areas, restoring damaged ecosystems, and sharing with other species much of the land we dominate.